Book/Report

FZJ-2019-01653

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Zwischenschichtkopplung in epitaktischen Fe-Schichtsystemen: Einfluß von Schichtwachstum, Grenzflächenrauhigkeit und paramagnetischen Einschlüssen

Schäfer, M. (Corresponding author)FZJ*

1996
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich

Please use a persistent id in citations: http://hdl.handle.net/2128/21734

Report No.: Juel-3290

Abstract: The subject of this study was an examination into the influences of interface and surface structure on the interlayer coupling, more specifically long and short period oscillation of interlayer coupling and biquadratic coupling. Critical to the study was the preparation and control of high quality epitaxial Fe/X/Fe sampies (X=Cr, Ag). The Fe/X/Fe was layered onto a composition of a GaAs substrates with an Fe seed layer and an Ag buffer layer. It was important to observe the influence of the temperature T$_{s}$ on the sample structure, therefore during growth process of the samples temperatures variances were introduced ranging from 100 K to 523 K. In order to preserve quality of the samples over the length of the study, the samples were prepared and stored in an ultra high vacuum environment. The surface structure of the Fe/X/Fe-Iayers was investigated in-situ with SPA-LEED and RREED. The interface structure was investigated ex-situ with x-ray diffraction. The magnetic properties were studied using an improved magneto-optic hysteresis loop technique developed specifically for this study. The results of the structural examination of the first Fe-Iayer surface was the discovery of a ring structure in the SPA-LEED pattern. These patterns demonstrate, that the Fe-surface structure is regularly terraced. Numerical analysis of this pattern concluded that the terraces were grouped in 5 open layers with a terrace step width of 5 (T$_{s}$ = 300 K) to 25 (T$_{s}$ = 523 K) lattice constants. These results remained constant after depositing an additional Cr-Iayer on top of this Fe-Iayer with a Cr-thickness ranging from 4 to 12 atomic layers. Upon examination of the Ag located on top of the first Fe-Iayer deviations were found to exist. First, no ring structure in the SPA-LEED pattern nor a corresponding spot splitting in the RREED pattern was observed. Secondly, an increase in the number of open layers from 5 to 7 was found and a decrease within the terrace step width from 5 down to 1-2 (T$_{s}$ = 300 K) to 25 down to 10 (T$_{s}$ = 523 K). The x-ray diffarction studies on the interface structures showed that the correlationlength for the Fe/Cr/Fe-Iayer grown at T$_{s}$ = 300 K was on average 1-2 lattice constants while it was 45 lattice constants for the sampies grown at T$_{s}$ = 523 K. In reference to interlayer coupling, samples grown at T$_{s}$ = 523 K revealed short and long period oscillations while samples grown at T$_{s}$ = 300 K revealed only long period oscillations. The observed interlayer coupling with respect to short and long period oscillations is explained by the data obtained from both the surface structure analysis and the interface structure analysis. In the process of examing the biquadratic coupling it was observed that Fe/Cr/Fe-samples grown at T$_{s}$ = 523 K followed SLONCZEWSKI'S fluctuation mechanism but the Fe/Cr/Fe-samples grown at T$_{s}$ = 300 K and the Fe/ Ag/Fe-samples at all temperatures did not fit the assumption of the model because of their poor surface and interface quality. A second model explaining biquadratic coupling, SLONCZEWSKI'S looose spin model,was studied by developing a second typ of samples. These samples were developed by evaporating additional Fe at low concentrations into the Ag spacer. The models predictions were observed experimentally within these sampies. Biquadratic coupling was observed to be dependend upon measurement temperature and loose spin concentration.

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Contributing Institute(s):

1. Publikationen vor 2000 (PRE-2000)

Research Program(s):

1. 899 - ohne Topic (POF3-899) (POF3-899)

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